Mechanical Dissipation in Silicon Flexures

The search for gravitational radiation remains one of the most challenging problems faced by experimental physicists at this present time. One of the most significant limits to the sensitivity of current and planned long-baseline gravitational wave detectors is thermal displacement noise in their test masses and suspensions. Future detectors with higher sensitivities will require optics with both reduced thermal noise and the capability of handling increased levels of laser power. The thermomechanical properties of silicon both at room and low temperatures make it of significant interest as a possible material for mirror substrates and suspension elements. The mechanical dissipation in a 91μm thick <110> single-crystal silicon cantilever has been observed over the temperature range 85 K to 300 K, with dissipations approaching levels down to φ = 4.4×10.